Control for electric blankets



TORNEYS 1 l INVENTOR.

BY 'Az /7 /6 FLUORESZENT TUBE Guy /7. AV/geyer' TO BEANKET G H ALLGEYER CONTROL FOR ELECTRIUBLANKETS Filed March 30, 1949 April 10, 1951 Patented Apr. 10, 1951 2,548,760 CONTROL FOR ELECTRIC BLANKETS Guy H. Allgeyer, Toledo, Ohio, assignor to The Swartzbaugh Manufacturing Company, Toledo, Ohio, a corporation of Ohio Application March 30, 19519, Serial No. 84,351

3 Claims. 1

This invention relates to controls for electric blankets and, more particularly, to a control for an electric blanket which is designed to facilitate its use by the person enjoying the electric blanket.

Many controls for electric blankets are provided with manually settable dials for controlling the setting of a bimetallic thermostat and thus controlling the temperatures at which the blanket is energized. and de-energized to maintain a substantially level heat beneath the blanket. Most of these dials or controls have been made small and difficult to grasp and have not been provided with any means by which the sleeper can see the control without turning on a light in the room. Furthermore, since such controls ordinarily are placed on the floor adjacent the bed or on a night stand, even if the sleeper does turn on a light to see the control it often is awkward for him to raise himself in the bed or to lean over the bed or to pick up the control to bring it in his line of vision. Some of the controls are so small as to necessitate the use of both hands, one to hold the control box and one to turn the handle or control.

It is the principal object of this invention to provide a control box for an electric blanket so designed as to enable the user to determine the setting of the control without the necessity for illuminating the room and even without the necessity for seeing the control at all.

It is another object of this invention to provide a control box for an electric blanket which will enable the user to change the setting a desired amount, as when he becomes cold or too warm, without the necessity of observing the control box at all.

These objects are accomplished by providing an electric control box in which the user can, if he desires, see the setting without illuminating the room or can hear or feel the changes of setting as they are made.

These objects, as well as more specific advantages, will be apparent from the description and from the drawings, in which:

Figure I is a view in elevation of a control box embodying the invention.

Figure II is a vertical sectional view taken substantially on the line IIII of Figure I.

Figure III is a vertical sectional view taken substantially on the line III-III in Figure I.

Figure IV is an enlarged fragmentary vertical sectional View showing an on-oil switch.

Figure V is a schematic wiring diagram illus- 2 trating the electrical circuits contained within the blanket control box.

A control box embodying the invention may have a molded or otherwise formed housing I, which has an approximately fiat top surface 2 including formed decorative features such as the ribs 3 or other features. Centrally located and near one end of the box is an on-01f switch 4 which, in the embodiment illustrated in the drawings, consists of a rockable member 5 that protrudes above the surface 2 and which can be moved from its on position to its off position by merely a downward pressure on the proper one of two arms 6 and 1 which alternately protrude above the surface 2 depending upon the setting of the switch. The member 5 has a small shoulder 3 engaged with a formed spring 9, the other end of which is hooked behind a lip 10 formed on a frame member ll located within the box. The spring 5 biases the switch 4 toward the off position acting also as an overcenter device to insure that the switch is either fully in the closed or in the opened position. A leaf contact I2 is engaged with an arcuate surface [3 formed on the underside of the rocker 5 and, when the switch is in the on position as illustrated in Figure IV, is moved downwardly into contact with a stationary contact arm [4 to close the principal circuit.

The stationary contact arm I4 is riveted or otherwise secured to the frame member [I (see Figure II) and also carries at its outermost end a contact point l5 and is connected by a lead iii to a small fluorescent tube H, the other side of which is connected by a lead I 8 to the power line. The fluorescent tube ii is mounted on a small bracket 19 secured again to the frame member l l.

A bimetallic leaf 20 having a contact point 2i adjacent the contact is mounted upcn a flexible bracket 22 for movement up and down, toward and away from the contact it both by the flexing of the bimetallic leaf and by adjustment in the position of the bracket 22. The contacts I5 and 2| normally are closed. A small heating coil 23 also is mounted upon the flexible bracket 22 and located immediately beneath the bimetallic portion of the leaf 2D.

The bimetallic leaf 2!] is connected by a lead 24 to one side of the coil 23 and through the coil 23 to a lead 25 which is connected to the blanket. Another lead 26 from the blanket is connected to the power line. Thus when the switch 4 is closed, current flows through the circuit and the heating coil 23 and the blanket are both energized and when the bimetallic strip is warped by heat generated in the coil 23 to open the contacts 2| and I5, both the heating coil and the blanket are de-energized. A condenser 21 is connected around the two contacts 2| and I5 to obviate arcing.

Control of the temperature at which the contacts l5 and 21 are opened by the warping of the bimetallic leaf 2!! is accomplished by adjusting the position of the flexible bracket 22 to reduce or increase the force with which the contacts are pressed together, thus biasing the bimetallic leaf more or less toward its open position. The adjustment is under the control of a hand knob 28 which, in the embodiment shown, is molded from a synthetic resin and has a profile such as to leave a relatively thin annular section 29 on its upper surface. The resin from which the knob 28 is molded is selected from the group of resins as, for example, the urea-formaldehyde resins, which are translucent in thin sections and thus, although there is great flexibility in the color of such resins, they remain sufficiently translucent to serve the purpose of indicating the setting of the dial in the manner to be explained. The knob 28 is mounted upon a vertical stud 30 which is threaded into a nut 3| secured to the underside of the frame member I I and which thus moves vertically when the knob 28 is rotated. The lower end of the stud 30 has a projection 32 which bears directly on an arm 33 of the flexible bracket 22. Thus, as the knob 28 is rotated the flexible bracket 22 is moved up or down as the case might be to relieve or increase the pressure between the two contacts 15 and 2|, thus decreasing or increasing the amount of heat necessary to warp the bimetallic leaf 2i! sufficiently to open the contacts [5 and 2! and ole-energize the coil 23 and the blanket.

The knob 28 is so located that its annular translucent area 29 is positioned immediately above the location of the small fluorescent tube ll. A focusing lens 36 is positioned immediately above the fluorescent tube ll in an aperture in the housing l to direct a beam of light onto the undersurface of the annular area 29. On the annular area 253 there is imprinted a series of numerical or other indicia which indicate relative settings of the blanket. These indicia do not show the particular temperature at which the blanket will be maintained because this temperature varies, of course, due to ambient temperatures in the room in which the blanket is located and whether or not other covers are placed on top of the blanket, etc. However, for the same room conditions and for the same conditions relative to the blanket itself, the user can find with but little experimentation that the blanket is comfortable with, say, the number 3 or the number 4 centered on the illuminated spot which appears immediately above the lens 34 in the translucent area 29 of the knob 28. If he becomes cooler or warmer, a change either upwardly or downwardly can be made to change the blanket temperature. Other indicia such as the designations high and low, with or without arrows indicating the direction of rotation or similar indicia designed for the same purpose can, of course, be printed in opaque material on the translucent surface 29 of the knob 28. Immediately upon closure of the switch 3 the tube H is illuminated throwing the spot of light through the lens 34 onto the underside of the knob 28 and outlining against the light that one of the indicia 35 positioned thereabove. The user thus can immediately tell whether or not the blanket is set at the same control point where he found it most comfortable in past usage without the necessity for picking up the control box and examining it closely and the knob 28 need not have its position changed from one day to the next during the use of the blanket.

In some circumstances it is inconvenient for the user to lean over the edge of the bed or to lift himself up in bed to see the position of the knob or to enable himself to turn the knob say, one step in either direction if he becomes either too warm or too cold. For this reason the present invention provides means by which the degree of change of the position of the knob 28 can be heard and felt. These means consist in an arm 36, preferably formed of a resilient material which is clipped around a molded hub 31 of the knob 28 and has a detent-like end 38 which is engageable in any one of a series of depressions 39 formed in the upper surface 2. The arm 36 is engageable against opposite sides of a stop 40 embedded in the surface 2 of the housing I to form limits for the rotation of the knob 28.

As the knob 28 is rotated the user can hear the clicking sound of the arm 36 as its formed detent snaps into and out of the depressions 39. Thus rotation from a previous position until the next click is heard by the user indicates that the seting of the knob has been advanced or retarded, say, one step or perhaps one-half of one step between successive ones of the numerals constituting the indicia 35 and thus between successive steps in relative temperatures controlled by the knob 28. Similarly, as the knob is rotated at user can feel the relative ease of rotation caused by engagement and disengagement of the detent portion of the arm 36 and.

successive depressions 39 and even if he cannot hear the click of the detent moving into and out of the depressions, he can feel this change and can determine, without the necessity for viewing the control box, that he has advanced or retarded the blanket control by one or more steps in temperature.

The embodiment of the invention which has been described is but one of the many forms which may be adopted employing other materials for the housing, other shapes for the relative parts thereof and other parts for the control and indicating knob all within the spirit and scope of the claims that follow.

Having described the invention, I'claim:

1. A control for a bed covering having an electrical heating coil and an adjustable temperature responsive circuit closing and opening element that comprises a housing for enclosing said temperature responsive element, a light source in said housing, a rotatable control knob mounted on the exterior of said housing, said knob having an annular translucent area with relatively opaque indicia imprinted thereon, said light source serving to illuminate that one of said indicia positioned adjacent thereto at any time, detent means rotatable with said knob and a series of depressions in said housing audibly engaged by said detent when said knob is rotated for positioning said knob'and for signalling the degree of rotation of said knob audibly and tactilly.

2. Control means for an electrically heated blanket having an adjustable thermostat for controlling the temperature thereof comprising, in combination, a housing, a lamp mounted in said housin in parallel with said thermostat, a knob for adjusting said thermostat, said knob being rotatably mounted on said housing, and having an annular relatively translucent area, means on said housing beneath said knob for focusing the light from said lamp in a path intersecting said area on said knob, a series of relatively opaque knob-setting indicia sequentially arranged on said area in position to be serially moved into the light focused by said means, and detent means rotatable with said knob, said housing having a series of depressions corresponding to said indicia, each being audibly and tactilly engaged by said detent means when its associated indicium is in the path of light focused by said focusing means.

3. A manually operable control for setting a thermostatic switch for an electrical heating device, said switch comprising a thermally responsive contact bearing element, a stationary contact and rotatable means for positioning said contacts relative to each other; said control having a casing enclosing the contacts and the rotatable means protruding through an opening REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,243,915 Barnes Oct. 23, 1917 1,566,069 Buchholz et a1 Dec. 15, 1925 1,950,324 Powers Mar. 6, 1934 2,299,462 Clark et al Oct. 20, 1942 2,383,291 Cook Aug. 21, 1945 2,429,475 McNairy et a1 Oct. 21, 1947 

